JP5456928B2 - Nitride semiconductor light emitting device - Google Patents

Description

  The present invention relates to a nitride semiconductor light emitting device and a method for manufacturing a nitride semiconductor light emitting device.

  In general, nitride semiconductor laser elements among nitride semiconductor light emitting elements are known to have poor reliability due to deterioration of the light emitting portion. It is said that the deterioration of the light emitting part is caused by excessive heat generation of the light emitting part due to the presence of the non-radiative recombination level. As a main factor for generating the non-radiative recombination level, oxidation of the light emitting portion is considered.

Therefore, for the purpose of preventing oxidation of the light emitting portion, a coat film such as alumina (Al ₂ O ₃ ) or silicon oxide (SiO ₂ ) is formed on the light emitting portion (see, for example, Patent Document 1). .

JP 2002-335053 A

  We have conducted research aiming to realize a nitride semiconductor laser device that does not cause poor reliability due to deterioration of the light emitting portion even during high-power driving.

  A conventional nitridation is formed by forming a coat film made of alumina on the end face on the light emitting side to a thickness of 80 nm and forming a multilayer film of silicon oxide film / titanium oxide film on the end face on the light reflecting side to achieve a reflectivity of 95%. Aging test (30 ° C., CW drive, optical output 30 mW) under low temperature and low output conditions and aging test (70 ° C., CW drive, optical output 100 mW) under high temperature and high output conditions for semiconductor laser devices Two types of aging tests were performed. As a result, in the aging test under the condition of low temperature and low output, the operation was stable even after 3000 hours. However, in the aging test under the condition of high temperature and high output, the light was observed from around 400 hours. Many nitride semiconductor laser elements that stop the oscillation of laser light due to COD (Catastrophic Optical Damage) at the emission part were observed. Accordingly, it has been found that in the conventional nitride semiconductor laser device, the COD of the light emitting portion becomes a problem with a relatively short aging time of 400 hours under the condition of high temperature and high output.

  Further, even when the nitride semiconductor light emitting diode element is driven under conditions of high temperature and high output, it is conceivable that the light emitting surface as the light emitting portion is deteriorated and reliability is lowered.

  There is also a demand for improved reliability in nitride semiconductor transistor elements such as HFET (Heterostructure Field Effect Transistor) using nitride semiconductors.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a nitride semiconductor light emitting device capable of obtaining sufficient reliability even at high temperature and high output driving, and a method for manufacturing a nitride semiconductor light emitting device for manufacturing the nitride semiconductor light emitting device. An object of the present invention is to provide a nitride semiconductor transistor device capable of improving reliability.

  The present invention provides a nitride semiconductor light emitting device in which a coat film is formed at a light emitting portion, wherein the coat film is made of an aluminum nitride crystal or an aluminum oxynitride crystal, and further the coat film Is characterized in that the crystal axis is aligned with the nitride semiconductor crystal constituting the light emitting portion.

  It is preferable that an amorphous film is formed on the coating film.

  According to the present invention, a nitride semiconductor light emitting device capable of obtaining sufficient reliability even at high temperature and high output drive, a method for manufacturing a nitride semiconductor light emitting device for manufacturing the nitride semiconductor light emitting device, and A nitride semiconductor transistor device capable of improving reliability can be provided.

FIG. 3 is a schematic cross-sectional view of a preferred example of the nitride semiconductor laser element of the present invention. FIG. 2 is a schematic side view of the nitride semiconductor laser element shown in FIG. 1 in the cavity length direction. It is a typical block diagram of an example of an ECR sputtering film-forming apparatus. 3 is a TEM photograph of the vicinity of the end surface on the light emission side of the nitride semiconductor laser element according to the first embodiment. It is an electron beam diffraction pattern by TEM of the area | region A shown in FIG. It is an electron beam diffraction pattern by TEM of the area | region B shown in FIG. FIG. 6 is a result of investigating COD levels before and after aging of the nitride semiconductor laser element of the first embodiment. FIG. It is a figure which shows the relationship between the aging time of the conventional nitride semiconductor laser element, and a COD level. It is typical sectional drawing of a preferable example of the nitride semiconductor transistor element of this invention. FIG. 3 is a schematic cross-sectional view illustrating an example of peeling of a film on an end face of a nitride semiconductor laser element.

  Embodiments of the present invention will be described below. In the drawings of the present invention, the same reference numerals represent the same or corresponding parts.

  In order to solve the above problem, the present inventor has performed aging under conditions of low temperature and low output (30 ° C., CW drive, light output 30 mW) and conditions of high temperature and high output (70 ° C., CW drive, light The change in the COD level of the conventional nitride semiconductor laser element having the above-described configuration after aging at an output of 100 mW was examined.

  FIG. 8 shows the relationship between the aging time and the COD level of a conventional nitride semiconductor laser device. In FIG. 8, the horizontal axis indicates the aging time, and the vertical axis indicates the COD level. Here, the COD level is obtained when the light output is increased by gradually increasing the drive current (CW drive) for each nitride semiconductor laser element after aging by changing the aging time under the above conditions. The light output value when the light emitting part CODs.

  As shown in FIG. 8, in the nitride semiconductor laser element after aging under low temperature and low output conditions, the aging time is about 50 hours, and the light emitting portion is deteriorated by COD. Even with increasing length, the COD level has hardly changed.

  On the other hand, even in a nitride semiconductor laser element after aging under high temperature and high output conditions, degradation of the light emitting portion due to COD occurs in about 50 hours, and the COD level greatly decreases until the aging time is about 200 hours. do not do. However, when the aging time exceeds 400 hours, the COD level is greatly reduced.

  From the above results, the present inventor is the cause of the decrease in the reliability of the nitride semiconductor laser device due to the decrease in the COD level after aging time of 400 hours or more in aging under high temperature and high output conditions. I understood it.

  The inventor transmits oxygen or O—H groups in the atmosphere through a coating film made of alumina formed on the end surface on the light emitting side to form a surface of the nitride semiconductor crystal constituting the end surface on the light emitting side. It was considered that the COD level was lowered because the nitride semiconductor crystal was oxidized. That is, it is considered that it took about 400 hours for oxygen or O—H groups in the atmosphere to pass through the 80 nm-thick coat film made of alumina.

  In most cases, the coating film formed on the end face on the light emitting side is formed using a method such as an EB (Electron Beam) vapor deposition method or a sputtering method. In this case, it is known that the coating film is almost amorphous. When TEM (Transmission Electron Microscopy) observation was performed on the end face of the nitride semiconductor laser element after the above test and the electron diffraction pattern of the coating film was observed, a halo pattern peculiar to the amorphous was observed, and the coating film was It was confirmed to be amorphous.

  Therefore, the present inventor considered that the amorphous coating film has a low density and contains many defects, so that it may easily transmit oxygen or O—H groups in the atmosphere. As a result of intensive studies by the present inventors, by forming a coating film containing an aluminum nitride crystal or an aluminum oxynitride crystal in the light emitting portion of the nitride semiconductor light emitting device, high temperature and high output driving can be achieved. It has been found that sufficient reliability can be obtained, and the present invention has been completed.

  Further, as a result of intensive studies by the present inventors, the crystal axis of the aluminum nitride crystal or the aluminum oxynitride crystal in the coating film is aligned with the crystal axis of the nitride semiconductor crystal constituting the light emitting portion. In some cases, it has been found that reliability can be further improved in high temperature and high output driving.

  In the present invention, the thickness of the coat film is preferably 6 nm or more and 150 nm or less. When the thickness of the coat film is less than 6 nm, the thickness of the coat film is so thin that oxygen or the like may not be sufficiently prevented from passing through the coat film. In addition, when the thickness of the coating film exceeds 150 nm, the crystallized coating film has a stronger internal stress than that of the amorphous film, which may cause problems such as cracks in the coating film. There is.

  In the present invention, when the oxygen content of the coat film made of an oxynitride crystal of aluminum is more than 35 atomic% of the total atoms constituting the coat film, the coat film approaches the characteristics of alumina, and aluminum The crystallinity of the oxynitride crystal is broken, and oxygen or the like tends not to be sufficiently suppressed from permeating through the coat film. Therefore, in the present invention, the oxygen content in the coat film made of aluminum oxynitride crystal is preferably 35 atomic% or less, and more preferably 15 atomic% or less.

  Here, examples of the nitride semiconductor light emitting device of the present invention include a nitride semiconductor laser device and a nitride semiconductor light emitting diode device. In the nitride semiconductor light emitting device of the present invention, the active layer and the cladding layer formed on the substrate are at least one group 3 element and group 5 element selected from the group consisting of aluminum, indium and gallium. It means a light emitting device composed of a material containing 50% by mass or more of a compound with nitrogen.

  The nitride semiconductor transistor element of the present invention includes, for example, an HFET using a nitride semiconductor.

(Embodiment 1)
FIG. 1 shows a schematic cross-sectional view of a preferred example of the nitride semiconductor laser element of the present embodiment. Here, the nitride semiconductor laser device 100 according to the present embodiment includes a buffer layer 102 made of n-type GaN having a thickness of 0.2 μm and an n-type Al _0.06 Ga _0.94 N on a semiconductor substrate 101 made of n-type GaN. An n-type cladding layer 103 having a thickness of 2.3 μm, an n-type guide layer 104 having a thickness of 0.02 μm made of n-type GaN, a multi-quantum well active layer 105 made of InGaN having a thickness of 4 nm and GaN having a thickness of 8 nm, A p-type current blocking layer 106 having a thickness of 20 nm made of p-type Al _0.3 Ga _0.7 N, a p-type cladding layer 107 having a thickness of 0.5 μm made of p-type Al _0.05 Ga _0.95 N, and a thickness of 0.1 μm made of p-type GaN. A 1 μm p-type contact layer 108 is stacked by epitaxial growth in this order from the semiconductor substrate 101 side. In addition, the mixed crystal ratio of each said layer is adjusted suitably, and is not related to the essence of this invention. Further, the wavelength of the laser light oscillated from the nitride semiconductor laser element of the present embodiment can be adjusted as appropriate within a range of 370 nm to 470 nm, for example, depending on the mixed crystal ratio of the multiple quantum well active layer 105. In the present embodiment, the wavelength of the laser light is 405 nm.

  Further, in the nitride semiconductor laser device 100 of the present embodiment, the p-type cladding layer 107 and the p-type contact layer 108 are partially removed so that the striped ridge stripe portion 111 extends in the cavity length direction. Is formed. Here, the width of the stripe of the ridge stripe portion 111 is, for example, about 1.2 to 2.4 μm, and typically about 1.5 μm.

Further, a p-electrode 110 made of a laminate of a Pd layer, a Mo layer, and an Au layer is provided on the surface of the p-type contact layer 108, and a SiO ₂ layer is formed below the p-electrode 110 except for a portion where the ridge stripe portion 111 is formed. An insulating film 109 made of a laminate of a layer and a TiO ₂ layer is provided. In addition, an n-electrode 112 made of a laminate of an Hf layer and an Al layer is formed on the surface of the n-type GaN substrate 101 opposite to the layer on the layer side.

FIG. 2 is a schematic side view of the nitride semiconductor laser element of the present embodiment shown in FIG. 1 in the cavity length direction. Here, the end surface 113 on the light emitting side of the nitride semiconductor laser device 100 of the present embodiment is made of aluminum expressed by a composition formula of Al _{a Ob} N _c (a + b + c = 1, 0 <b ≦ 0.35). A coat film 114 made of oxynitride is formed with a thickness of 6 nm, and an aluminum oxide film 115 is formed with a thickness of 80 nm on the coat film 114. In the above composition formula, Al represents aluminum, O represents oxygen, and N represents nitrogen. In the above composition formula, a represents the composition ratio of aluminum, b represents the composition ratio of oxygen, and c represents the composition ratio of nitrogen. When the coat film is formed by the sputtering method, argon or the like may be included to some extent, but here, it is expressed in terms of a composition ratio excluding argon other than Al, O, and N. That is, the sum of the composition ratios of Al, O, and N is set to 1.

  The end surface 116 on the light reflection side of the nitride semiconductor laser device 100 of the present embodiment has an aluminum oxynitride film 117 having a thickness of 6 nm, an aluminum oxide film 118 having a thickness of 80 nm, and a thickness of 71 nm. This is a high reflection film 119 in which a silicon oxide film and a 46 nm-thick titanium oxide film are stacked as a pair, and four pairs are stacked (lamination starts from the silicon oxide film), and then a 142 nm-thick silicon oxide film is stacked on the outermost surface. Formed in order.

  The coating film 114, the aluminum oxide film 115, the aluminum oxynitride film 117, the aluminum oxide film 118, and the highly reflective film 119 are formed on the semiconductor substrate by using the above-described nitride such as a buffer layer. After sequentially laminating the semiconductor layers and forming the ridge stripe portion, the wafer on which the insulating film, the p-electrode, and the n-electrode are formed is cleaved to prepare a sample in which the end face 113 and the end face 116 that are cleavage faces are exposed. , Formed on the end face 113 and the end face 116 of the sample, respectively.

  Before the coating film 114 is formed, the end surface 113 is heated at a temperature of, for example, 100 ° C. or higher in the film forming apparatus, thereby removing the oxide film and impurities attached to the end surface 113 and cleaning the surface. Although it is preferable, it is not particularly necessary in the present invention. Further, the end face 113 may be cleaned by irradiating the end face 113 with, for example, argon or nitrogen plasma, but this is not particularly necessary in the present invention. It is also possible to irradiate plasma while heating the end face 113. As for the above-described plasma irradiation, for example, it is possible to irradiate nitrogen plasma after irradiating argon plasma, and the plasma may be irradiated in the reverse order. In addition to argon and nitrogen, for example, a rare gas such as helium, neon, xenon, or krypton can be used.

  The coating film 114 can be formed by, for example, an ECR (Electron Cyclotron Resonance) sputtering method described below. However, other various sputtering methods, a CVD (Chemical Vapor Deposition) method, or an EB (Electron Beam) method can be used. It can also be formed by vapor deposition.

  FIG. 3 shows a schematic configuration diagram of an example of an ECR sputtering film forming apparatus. Here, the ECR sputtering film forming apparatus includes a film forming chamber 200, a magnetic coil 203, and a microwave introduction window 202. A gas introduction port 201 and a gas exhaust port 209 are installed in the film forming chamber 200, and an Al target 204 and a heater 205 connected to an RF power source 208 are installed in the film forming chamber 200. A sample stage 207 is installed in the film forming chamber 200, and the sample 206 is installed on the sample stage 207. The magnetic coil 203 is provided for generating a magnetic field necessary for generating plasma, and the RF power source 208 is used for sputtering the Al target 204. Further, the microwave 210 is introduced into the film forming chamber 200 through the microwave introduction window 202.

  Then, nitrogen gas is introduced into the film formation chamber 200 from the gas introduction port 201 at a flow rate of 5.2 sccm, oxygen gas is introduced at a flow rate of 1.0 sccm, and plasma is efficiently generated to increase the film formation rate. In order to enlarge, argon gas is introduced at a flow rate of 20.0 sccm. Note that the oxygen content in the coating film 114 can be changed by changing the ratio of nitrogen gas to oxygen gas in the growth chamber 200. In addition, when 500 W of RF power is applied to the Al target 204 to sputter the Al target 204 and 500 W of microwave power necessary for plasma generation is applied, the film formation rate is 1.7 Å / second, the wavelength A coating film 114 made of an aluminum oxynitride having a refractive index of light of 405 nm of 2.1 can be formed. The contents (atomic%) of aluminum, nitrogen and oxygen constituting the coating film 114 can be measured by, for example, AES (Auger Electron Spectroscopy). The content of oxygen constituting the coating film 114 can also be measured by TEM-EDX (Transmission Electron Microscopy-Energy Dispersive X-ray Spectroscopy).

  As a result of analyzing the composition of aluminum oxynitride separately produced in the thickness direction by AES under the same conditions as described above, the content of aluminum constituting the aluminum oxynitride was 34.8 atomic%, It was found that the content was 3.8 atomic% and the nitrogen content was 61.4 atomic%, and the composition was almost uniform in the thickness direction. A very small amount of argon was also detected. Here, argon is a part of the argon gas introduced into the film formation chamber 200 for sputtering the Al target 204. Further, when the total number of atoms of aluminum, oxygen, nitrogen and argon in the coating film 114 is 100 atomic%, the argon content in the coating film 114 is in the range of more than 0 atomic% and less than 5 atomic%. Usually, it is about 1 atom% or more and 3 atom% or less, but the present invention is not limited to this.

  Further, the aluminum oxide film 115 on the light emitting side, the aluminum oxynitride film 117 on the light reflecting side, the aluminum oxide film 118 and the highly reflective film 119 are also formed by the ECR sputtering method or the like in the same manner as the coating film 114 described above. Can be formed. Also, it is preferable to perform cleaning by heating and / or cleaning by plasma irradiation before forming these films. However, the deterioration of the light emitting portion is a problem on the light emitting side where the light density is large, and the light reflecting side has a light density lower than that on the light emitting side, so that deterioration is not a problem in many cases. Therefore, in the present invention, a film such as an aluminum oxynitride film may not be provided on the end surface 116 on the light reflection side. In this embodiment, aluminum oxynitride 117 having a thickness of 6 nm is formed on end surface 116 on the light reflection side. The thickness of aluminum oxynitride 117 is, for example, as thick as 50 nm. There is no problem.

  Further, after the above film is formed on the end face, heat treatment may be performed. As a result, it is possible to expect an improvement in film quality due to the removal of moisture contained in the film and the heat treatment.

  As described above, the coating film 114 and the aluminum oxide film 115 are formed in this order on the end surface 113 on the light emitting side of the above sample, and the aluminum oxynitride film 117 and aluminum are formed on the end surface 116 on the light reflecting side. The oxide film 118 and the highly reflective film 119 are formed in this order and then divided into chips to obtain the nitride semiconductor laser device of the present embodiment.

  FIG. 4 shows a TEM photograph in the vicinity of the end face on the light emission side of the nitride semiconductor laser element of the present embodiment. 5 shows an electron beam diffraction pattern of the region A shown in FIG. 4 by TEM, and FIG. 6 shows an electron beam diffraction pattern of the region B shown in FIG. 4 by TEM. A region B shown in FIG. 4 extends over two regions of the light emitting side end face 113 and the coating film 114, and in FIG. 6, the spot diameter is narrowed down in order to separate diffraction images from these two regions.

  As shown in FIG. 5, since this electron beam diffraction pattern is dotted with diffraction spots, it can be seen that the region A of the coating film 114 made of aluminum oxynitride is crystallized.

  Further, the arrows shown in FIG. 6 indicate the diffraction spots of the coat film 114 in the region B. As shown in FIG. 6, the diffraction spots of the coat film 114 form the nitride semiconductor crystal constituting the end face 113 on the light emission side. It almost coincides with the diffraction spot. Therefore, it was confirmed that the crystal axes of the nitride semiconductor crystal constituting the end face 113 on the light emitting side and the aluminum oxynitride crystal constituting the coat film 114 were aligned.

  Here, strictly speaking, FIG. 6 does not compare the diffraction spots of the light emitting portion of the nitride semiconductor laser element of the present embodiment and the coat film 114, but the end face 113 on the light emitting side is Since the nitride semiconductor layer is the end face of the wafer formed by epitaxial growth sequentially, it is considered that all the crystal axes of the nitride semiconductor crystals constituting the end face 113 on the light emitting side are aligned. Therefore, the crystal axis of the nitride semiconductor crystal constituting the light emitting portion which is a part of the end surface 113 on the light emitting side of the nitride semiconductor laser element of the present embodiment and the aluminum oxynitride crystal constituting the coat film 114 This is considered to be aligned with the crystal axis.

  In FIG. 6, the diffraction spot of the coat film 114 substantially coincides with the diffraction spot of the nitride semiconductor crystal constituting the end face 113 on the light emission side, but the nitride semiconductor constituting the end face 113 on the light emission side. Since the crystal and the aluminum oxynitride crystal constituting the coat film 114 have different lattice constants, the positions of these diffraction spots may be slightly shifted. In addition, in the central portion of FIG. 6, the diffraction spots of the nitride semiconductor crystal constituting the end surface 113 on the light emission side are large, and the diffraction spots of the coat film 114 are not visible.

  Table 1 shows the results obtained by determining the interplanar spacing of aluminum oxynitride crystals constituting the coating film 114 from the diffraction spots of the coating film 114 shown in FIG. The interplanar spacing of the aluminum nitride crystal shown on the JCPDS card as a reference is also shown. Here, the surface spacing in the C-axis direction of the coating film 114 manufactured in the present embodiment was 2.48 ohm strong (Å).

  The crystal system of the aluminum oxide film 115 on the coat film 114 was also examined by TEM and confirmed to be amorphous.

  The COD level before aging and after aging (70 ° C., CW drive, optical output 100 mW) of the nitride semiconductor laser device of this embodiment was investigated. The result is shown in FIG. As shown in FIG. 7, the COD level before aging is about 400 mW, and it can be seen that the COD level hardly decreases even when the aging time exceeds 400 hours.

  This is presumably because in the nitride semiconductor laser device of the present embodiment, the aluminum oxynitride crystal constituting the coat film 114 was epitaxially grown on the nitride semiconductor crystal constituting the end face 113 on the light emitting side. Such a highly crystalline film is effectively functioning as a film that suppresses the permeation of oxygen compared to an amorphous coating film that is thought to contain many defects. This is probably because of this.

In the above, a method for forming the coat film 114 made of an aluminum oxynitride represented by the composition formula of Al _a O _b N _c (a + b + c = 1, 0 <b ≦ 0.35) is shown in FIG. In place of the Al target 204, a target made of an aluminum oxide represented by a composition formula of Al _x O _y (0 <x <1, 0 <y <0.6) is used as the target. It is also possible to form nitrogen by reactive sputtering using nitrogen. In this case, the coat film 114 can be formed without intentionally introducing oxygen or the like into the film formation chamber 200. Since aluminum has a relatively high oxidizing property, when oxygen is introduced, composition control and reproducibility of the coating film 114 having a low oxygen content is difficult. However, the target is an aluminum oxide represented by a composition formula of Al _x O _y (0 <x <1, 0 <y <0.6), oxygen is not introduced into the film formation chamber 200, and only nitrogen is used. In the case of introduction, the coating film 114 having a low oxygen content can be formed relatively easily. Similar results can be obtained using a target made of aluminum oxynitride having a low oxygen content.

  Note that when a reactive sputtering apparatus is used, a microwave is applied in a state where an oxygen gas is introduced with a target made of aluminum installed in a film formation chamber without using an aluminum oxide target. By generating oxygen plasma and oxidizing the surface of the target made of aluminum with the oxygen plasma, a target made of aluminum oxide can be formed on the surface of the target made of aluminum.

  Further, for example, it is possible to form an aluminum oxynitride film using a target made of aluminum by the following Step 1 and Step 2.

Step 1
An oxygen gas is introduced into a film forming chamber of a reactive sputtering apparatus in which a target made of aluminum is installed, microwaves are applied to generate oxygen plasma, and the target made of aluminum is exposed to the oxygen plasma, thereby producing aluminum. Aluminum is oxidized to a depth of about several nm from the surface of the target made of aluminum, and a target made of aluminum oxide is formed on the surface of the target made of aluminum.

Step 2
Thereafter, nitrogen gas and argon gas are introduced into the film formation chamber, microwaves are applied to form a plasma state, and the aluminum oxynitride film is sputtered by the target made of the aluminum oxide prepared in step 1. Can be formed.

  In the above, a step of cleaning the surface of the nitride semiconductor by exposing it to plasma of argon gas, nitrogen gas, or a mixed gas of argon gas and nitrogen gas is added between step 1 and step 2. Also good.

(Embodiment 2)
The nitride semiconductor laser device of the present embodiment is the same as that of the first embodiment except that the configuration of the film formed on the end surface 113 on the light emission side and the configuration of the film formed on the end surface 116 on the light reflection side are changed. This has the same configuration as that of the nitride semiconductor laser device.

  In the nitride semiconductor laser device of the present embodiment, a coating film 114 made of aluminum nitride is formed on the end surface 113 on the light emitting side, and an aluminum oxide having a thickness of 200 nm is formed thereon. A film 115 is formed.

  Further, an aluminum nitride film having a thickness of 12 nm is formed on the end face 116 on the light reflection side, and an aluminum oxide film having a thickness of 80 nm is formed on the aluminum nitride film, and the aluminum oxide film is formed. 4 pairs of a silicon oxide film having a thickness of 81 nm and a titanium oxide film having a thickness of 54 nm are stacked on top of each other (lamination starts from the silicon oxide film), and then a silicon oxide film having a thickness of 162 nm is stacked on the outermost surface. A reflective film is formed.

  Here, in the same manner as in the first embodiment, when the crystal system of the coat film 114 was examined by the electron beam diffraction pattern of TEM, it was confirmed that the coat film 114 was composed of an aluminum nitride crystal. . It was also confirmed by the electron beam diffraction pattern of the TEM that the crystal axes of the nitride semiconductor crystal constituting the light exit side end face 113 and the aluminum nitride crystal constituting the coat film 114 were aligned.

  For the nitride semiconductor laser element of the present embodiment, the COD level after aging (70 ° C., CW drive, optical output 100 mW) was investigated as in the first embodiment. As a result, it was confirmed that the COD level of the nitride semiconductor laser element of this embodiment hardly decreased even after aging for 400 hours.

(Embodiment 3)
The nitride semiconductor laser device of the present embodiment is the same as that of the first embodiment except that the configuration of the film formed on the end surface 113 on the light emission side and the configuration of the film formed on the end surface 116 on the light reflection side are changed. This has the same configuration as that of the nitride semiconductor laser device.

In the nitride semiconductor laser device of the present embodiment, coat film 114 made of aluminum oxynitride represented by the composition formula of Al _0.33 O _0.11 N _0.56 is formed on end face 113 on the light emitting side. An aluminum oxide film 115 having a thickness of 240 nm is formed thereon.

  Further, an aluminum nitride film having a thickness of 12 nm is formed on the end face 116 on the light reflection side, and an aluminum oxide film having a thickness of 80 nm is formed on the aluminum nitride film, and the aluminum oxide film is formed. 4 pairs of a silicon oxide film having a thickness of 81 nm and a titanium oxide film having a thickness of 54 nm are stacked on top of each other (lamination starts from the silicon oxide film), and then a silicon oxide film having a thickness of 162 nm is stacked on the outermost surface. A reflective film is formed.

  Here, in the same manner as in the first embodiment, the crystal system of the coat film 114 was investigated by the electron beam diffraction pattern of TEM, and it was confirmed that the coat film 114 was composed of aluminum oxynitride crystals. It was. It was also confirmed by the electron beam diffraction pattern of the TEM that the crystal axes of the nitride semiconductor crystal constituting the light exit side end face 113 and the aluminum oxynitride crystal constituting the coat film 114 were aligned.

  For the nitride semiconductor laser element of the present embodiment, the COD level after aging (70 ° C., CW drive, optical output 100 mW) was investigated as in the first embodiment. As a result, it was confirmed that the COD level of the nitride semiconductor laser element of this embodiment hardly decreased even after aging for 400 hours.

(Embodiment 4)
In the nitride semiconductor laser device of the present embodiment, the configuration of the film formed on the end surface 113 on the light emitting side and the configuration of the film formed on the end surface 116 on the light reflecting side are changed, and the laser beam oscillated The structure is the same as that of the nitride semiconductor laser element of the first embodiment except that the wavelength is 460 nm.

  In the nitride semiconductor laser device of the present embodiment, only the 50 nm thick coat film 114 made of aluminum oxynitride is formed on the end surface 113 on the light emitting side, and the reflectance is about 10%. ing.

  Further, an aluminum oxynitride film having a thickness of 6 nm is formed on the end surface 116 on the light reflection side, and an aluminum oxide film having a thickness of 80 nm is formed on the aluminum oxynitride film. Four pairs of a silicon oxide film having a thickness of 81 nm and a titanium oxide film having a thickness of 54 nm are laminated on the material film as a pair, and then a silicon oxide film having a thickness of 162 nm is laminated on the outermost surface. A highly reflective film is formed.

  Here, in the same manner as in the first embodiment, the crystal system of the coat film 114 was investigated by the electron beam diffraction pattern of TEM, and it was confirmed that the coat film 114 was composed of aluminum oxynitride crystals. It was. It was also confirmed by the electron beam diffraction pattern of the TEM that the crystal axes of the nitride semiconductor crystal constituting the light exit side end face 113 and the aluminum oxynitride crystal constituting the coat film 114 were aligned.

  For the nitride semiconductor laser element of the present embodiment, the COD level after aging (70 ° C., CW drive, optical output 100 mW) was investigated as in the first embodiment. As a result, it was confirmed that the COD level of the nitride semiconductor laser element of this embodiment hardly decreased even after aging for 400 hours.

(Embodiment 5)
The nitride semiconductor laser device of the present embodiment is the same as that of the first embodiment except that the configuration of the film formed on the end surface 113 on the light emission side and the configuration of the film formed on the end surface 116 on the light reflection side are changed. This has the same configuration as that of the nitride semiconductor laser device.

In the nitride semiconductor laser device of the present embodiment, coat film 114 made of aluminum oxynitride represented by the composition formula of Al _0.30 O _0.25 N _0.45 is formed on end face 113 on the light emission side. A silicon nitride film having a thickness of 110 nm is formed on the coat film 114.

  Further, an aluminum oxynitride film having a thickness of 50 nm is formed on the end surface 116 on the light reflecting side, and a silicon oxide film having a thickness of 50 nm is formed on the aluminum oxynitride film, and the silicon oxide film is formed on the silicon oxide film. A highly reflective film in which a silicon oxide film having a thickness of 142 nm is laminated on the outermost surface after six pairs are laminated (lamination starts from a silicon oxide film) with a silicon oxide film having a thickness of 71 nm and a silicon nitride film having a thickness of 50 nm as one pair. Is formed.

  Since the silicon nitride film has higher moisture resistance and lower oxygen permeability than the silicon oxide film (that is, O—H groups and oxygen are less likely to diffuse than in the silicon oxide film), the silicon nitride film is formed on the coat film 114. By forming, the tendency which can suppress the oxidation of the end surface 113 of the light emission side by permeation | transmission of oxygen etc. becomes large.

  Here, the thickness of the silicon nitride film on the coat film 114 is preferably 5 nm or more, and more preferably 80 nm or more. When the thickness of the silicon nitride film on the coat film 114 is less than 5 nm, it tends to be difficult to form a uniform film on the surface of the coat film 114, and when it is 80 nm or more, oxygen diffusion is likely to occur. This is because the inhibitory effect tends to be higher.

  Here, in the same manner as in the first embodiment, the crystal system of the coat film 114 was investigated by the electron beam diffraction pattern of TEM, and it was confirmed that the coat film 114 was composed of aluminum oxynitride crystals. It was. It was also confirmed by the electron beam diffraction pattern of the TEM that the crystal axes of the nitride semiconductor crystal constituting the light exit side end face 113 and the aluminum oxynitride crystal constituting the coat film 114 were aligned.

  For the nitride semiconductor laser element of the present embodiment, the COD level after aging (70 ° C., CW drive, optical output 100 mW) was investigated as in the first embodiment. As a result, it was confirmed that the COD level of the nitride semiconductor laser element of this embodiment hardly decreased even after aging for 400 hours.

(Embodiment 6)
The nitride semiconductor laser device of the present embodiment is the same as that of the first embodiment except that the configuration of the film formed on the end surface 113 on the light emission side and the configuration of the film formed on the end surface 116 on the light reflection side are changed. This has the same configuration as that of the nitride semiconductor laser device.

In the nitride semiconductor laser device of the present embodiment, a coat film 114 made of aluminum oxynitride represented by the composition formula of Al _0.31 O _0.03 N _0.66 is formed on the end surface 113 on the light emitting side, A 140 nm thick silicon nitride film is formed on the coat film 114, and a 140 nm thick silicon oxide film is formed on the silicon nitride film. Here, the thickness of the silicon nitride film on the coat film 114 and the silicon oxide film on the silicon nitride film is preferably 5 nm or more, respectively. This is because, when the thickness of these films is less than 5 nm, it tends to be difficult to form a uniform film in a plane.

  Further, an aluminum oxynitride film having a thickness of 50 nm is formed on the end surface 116 on the light reflecting side, and a silicon oxide film having a thickness of 50 nm is formed on the aluminum oxynitride film, and the silicon oxide film is formed on the silicon oxide film. A highly reflective film in which a silicon oxide film having a thickness of 142 nm is laminated on the outermost surface after six pairs are laminated (lamination starts from a silicon oxide film) with a silicon oxide film having a thickness of 71 nm and a silicon nitride film having a thickness of 50 nm as one pair. Is formed.

  Here, in the same manner as in the first embodiment, the crystal system of the coat film 114 was investigated by the electron beam diffraction pattern of TEM, and it was confirmed that the coat film 114 was composed of aluminum oxynitride crystals. It was. It was also confirmed by the electron beam diffraction pattern of the TEM that the crystal axes of the nitride semiconductor crystal constituting the light exit side end face 113 and the aluminum oxynitride crystal constituting the coat film 114 were aligned.

  For the nitride semiconductor laser element of the present embodiment, the COD level after aging (70 ° C., CW drive, optical output 100 mW) was investigated as in the first embodiment. As a result, it was confirmed that the COD level of the nitride semiconductor laser element of this embodiment hardly decreased even after aging for 400 hours.

  In addition, the silicon oxide film, which is the outermost surface layer on the light emitting side end face 113 side of the nitride semiconductor laser device of the present embodiment, is replaced with an aluminum oxide film having a thickness of 140 nm and is aged in the same manner as described above (70). As a result of investigating the COD level after aging, CW driving, and optical output of 100 mW, it was confirmed that there was almost no decrease even after aging for 400 hours as described above.

(Embodiment 7)
The nitride semiconductor laser device of the present embodiment is the same as that of the first embodiment except that the configuration of the film formed on the end surface 113 on the light emission side and the configuration of the film formed on the end surface 116 on the light reflection side are changed. This has the same configuration as that of the nitride semiconductor laser device.

In the nitride semiconductor laser device of the present embodiment, a coat film 114 made of aluminum oxynitride represented by the composition formula of Al _0.32 O _0.08 N _0.60 is formed on the end surface 113 on the light emission side, A 140 nm thick silicon nitride film is formed on the coat film 114, and an aluminum oxide film having a thickness of 160 nm is formed on the silicon nitride film.

  Further, an aluminum oxynitride film having a thickness of 50 nm is formed on the end surface 116 on the light reflecting side, and a silicon oxide film having a thickness of 50 nm is formed on the aluminum oxynitride film, and the silicon oxide film is formed on the silicon oxide film. A highly reflective film in which a silicon oxide film having a thickness of 142 nm is laminated on the outermost surface after six pairs are laminated (lamination starts from a silicon oxide film) with a silicon oxide film having a thickness of 71 nm and a silicon nitride film having a thickness of 50 nm as one pair. Is formed.

  Here, in the same manner as in the first embodiment, the crystal system of the coat film 114 was investigated by the electron beam diffraction pattern of TEM, and it was confirmed that the coat film 114 was composed of aluminum oxynitride crystals. It was. It was also confirmed by the electron beam diffraction pattern of the TEM that the crystal axes of the nitride semiconductor crystal constituting the light exit side end face 113 and the aluminum oxynitride crystal constituting the coat film 114 were aligned.

  For the nitride semiconductor laser element of the present embodiment, the COD level after aging (70 ° C., CW drive, optical output 100 mW) was investigated as in the first embodiment. As a result, it was confirmed that the COD level of the nitride semiconductor laser element of this embodiment hardly decreased even after aging for 400 hours.

  In addition, the aluminum oxide film, which is the outermost surface layer on the end surface 113 side on the light emitting side of the nitride semiconductor laser element of the present embodiment, is replaced with a 140 nm thick silicon oxide film and is aged in the same manner as described above. When the COD level after (70 ° C., CW drive, optical output 100 mW) was investigated, it was confirmed that there was almost no decrease even after aging for 400 hours as described above.

(Embodiment 8)
The nitride semiconductor laser device of the present embodiment is the same as that of the first embodiment except that the configuration of the film formed on the end surface 113 on the light emission side and the configuration of the film formed on the end surface 116 on the light reflection side are changed. This has the same configuration as that of the nitride semiconductor laser device.

In the nitride semiconductor laser device of the present embodiment, a coat film 114 made of aluminum oxynitride represented by the composition formula of Al _0.32 O _0.08 N _0.60 is formed on the end surface 113 on the light emitting side, A silicon oxynitride film having a thickness of 230 nm is formed on the coat film 114. Here, the silicon oxynitride film on the coat film 114 is represented by a composition formula of Si _0.348 O _0.04 N _0.612 , the silicon content is 34.8 atomic%, and the oxygen content is 4.0 atomic%. The nitrogen content was 61.2 atomic%.

  Further, an aluminum oxynitride film having a thickness of 50 nm is formed on the end surface 116 on the light reflecting side, and a silicon oxide film having a thickness of 50 nm is formed on the aluminum oxynitride film, and the silicon oxide film is formed on the silicon oxide film. A highly reflective film in which a silicon oxide film having a thickness of 142 nm is laminated on the outermost surface after six pairs are laminated (lamination starts from a silicon oxide film) with a silicon oxide film having a thickness of 71 nm and a silicon nitride film having a thickness of 50 nm as one pair. Is formed.

  Here, in the same manner as in the first embodiment, the crystal system of the coat film 114 was investigated by the electron beam diffraction pattern of TEM, and it was confirmed that the coat film 114 was composed of aluminum oxynitride crystals. It was. It was also confirmed by the electron beam diffraction pattern of the TEM that the crystal axes of the nitride semiconductor crystal constituting the light exit side end face 113 and the aluminum oxynitride crystal constituting the coat film 114 were aligned.

  For the nitride semiconductor laser element of the present embodiment, the COD level after aging (70 ° C., CW drive, optical output 100 mW) was investigated as in the first embodiment. As a result, it was confirmed that the COD level of the nitride semiconductor laser element of this embodiment hardly decreased even after aging for 400 hours.

(Embodiment 9)
The nitride semiconductor laser device of the present embodiment is the same as that of the first embodiment except that the configuration of the film formed on the end surface 113 on the light emission side and the configuration of the film formed on the end surface 116 on the light reflection side are changed. This has the same configuration as that of the nitride semiconductor laser device.

In the nitride semiconductor laser device of the present embodiment, a coating film 114 having a thickness of 40 nm made of aluminum oxynitride represented by the composition formula of Al _0.32 O _0.08 N _0.60 is formed on the end surface 113 on the light emitting side, A zirconium oxide film having a thickness of 100 nm is formed on the coat film 114.

  Further, an aluminum oxynitride film having a thickness of 50 nm is formed on the end surface 116 on the light reflecting side, and a silicon oxide film having a thickness of 50 nm is formed on the aluminum oxynitride film, and the silicon oxide film is formed on the silicon oxide film. A highly reflective film in which a silicon oxide film having a thickness of 142 nm is laminated on the outermost surface after six pairs are laminated (lamination starts from a silicon oxide film) with a silicon oxide film having a thickness of 71 nm and a silicon nitride film having a thickness of 50 nm as one pair. Is formed.

  Here, in the same manner as in the first embodiment, the crystal system of the coat film 114 was investigated by the electron beam diffraction pattern of TEM, and it was confirmed that the coat film 114 was composed of aluminum oxynitride crystals. It was. It was also confirmed by the electron beam diffraction pattern of the TEM that the crystal axes of the nitride semiconductor crystal constituting the light exit side end face 113 and the aluminum oxynitride crystal constituting the coat film 114 were aligned.

  For the nitride semiconductor laser element of the present embodiment, the COD level after aging (70 ° C., CW drive, optical output 100 mW) was investigated as in the first embodiment. As a result, it was confirmed that the COD level of the nitride semiconductor laser element of this embodiment hardly decreased even after aging for 400 hours.

(Embodiment 10)
The nitride semiconductor laser device of the present embodiment is the same as that of the first embodiment except that the configuration of the film formed on the end surface 113 on the light emission side and the configuration of the film formed on the end surface 116 on the light reflection side are changed. This has the same configuration as that of the nitride semiconductor laser device.

  In the nitride semiconductor laser device of the present embodiment, a coat film 114 made of aluminum nitride is formed on end face 113 on the light emitting side, and a 140 nm thick silicon nitride film is formed on coat film 114. Is formed.

  Further, an aluminum nitride film having a thickness of 50 nm is formed on the end face 116 on the light reflection side, a silicon oxide film having a thickness of 50 nm is formed on the aluminum nitride film, and the thickness is formed on the silicon oxide film. Six pairs of a 71 nm silicon oxide film and a 50 nm thick silicon nitride film are stacked (starting from the silicon oxide film), and then a highly reflective film in which a 142 nm thick silicon oxide film is stacked on the outermost surface is formed. Has been.

  Here, in the same manner as in the first embodiment, when the crystal system of the coat film 114 was examined by the electron beam diffraction pattern of TEM, it was confirmed that the coat film 114 was composed of an aluminum nitride crystal. . It was also confirmed by the electron beam diffraction pattern of the TEM that the crystal axes of the nitride semiconductor crystal constituting the light exit side end face 113 and the aluminum nitride crystal constituting the coat film 114 were aligned.

  For the nitride semiconductor laser element of the present embodiment, the COD level after aging (70 ° C., CW drive, optical output 100 mW) was investigated as in the first embodiment. As a result, it was confirmed that the COD level of the nitride semiconductor laser element of this embodiment hardly decreased even after aging for 400 hours.

  Like the nitride semiconductor laser element of the present embodiment, the crystal axis is aligned with the nitride semiconductor crystal constituting the light emitting side end face 113 on the light emitting side end face 113 made of a nitride semiconductor crystal. In the case where the coat film 114 made of crystallized aluminum nitride crystal is formed, the film formed on the coat film 114 has a silicon nitride film or silicon oxynitride film rather than an oxide film. Or an aluminum oxynitride film is preferable from the viewpoint of improving reliability.

  Further, an appearance inspection of the end face portion of the nitride semiconductor laser element of the present embodiment (observation of the peeling state of the film formed on the end face of the nitride semiconductor laser element after being divided into chips is observed with a stereomicroscope or the like) Was done. At this time, in the nitride semiconductor laser element of the present embodiment, the light emission side is higher than that of the nitride semiconductor laser element of the second embodiment in which the aluminum oxide film is formed on the coat film 114 made of aluminum nitride. It has been confirmed that the occurrence of peeling of the film formed on the end face of the film can be reduced.

  Here, when a film made of an oxide was formed on the coat film 114 made of aluminum nitride, film peeling did not occur (hereinafter referred to as “film peeling yield”) of 88% of the total. When a film made of nitride or oxynitride was formed on the coat film 114 made of an aluminum nitride film, the yield of film peeling was 94% of the whole.

Such film peeling often occurs in a region indicated by C in the nitride semiconductor laser device shown in the schematic cross-sectional view of FIG. 10 when divided into chips, and the subsequent mounting step and / or aging is performed. In the test, peeling of the film further proceeds, causing defective products to be produced. The nitride semiconductor laser element shown in FIG. 10 has an insulating film 78 made of a laminated body of a SiO ₂ layer and a TiO ₂ layer for current confinement, and for injecting current. A p-side electrode 79 is provided.

  From the above viewpoint, when the coating film 114 is made of aluminum nitride, the film formed on the coating film 114 is more preferably nitride or oxynitride. In the case where the coat film 114 is made of aluminum oxynitride, the difference in film peeling due to the difference in the material of the film on the coat film 114 was not found, so that the coat film 114 is formed. It is also considered that aluminum oxynitride relaxes the difference in thermal expansion coefficient and internal stress.

  Further, by forming the insulating film 109 shown in FIG. 1 and the insulating film 78 shown in FIG. 10 for current confinement in the steps of the first to tenth embodiments, the end face of the nitride semiconductor laser device described above is formed. The yield of film peeling can be improved.

  In the nitride semiconductor laser element, peeling of the film near the ridge stripe portion is the most problematic, but when the insulating film formed on the side of the ridge stripe portion and the film formed on the end surface are in contact with each other, It was found that the film peeling near the ridge stripe portion can be effectively prevented. This is considered to be due to the fact that the strain is relieved at the portion where the insulating film is in contact with the film formed on the end face. Note that when the insulating film and the film formed on the end surface are not in contact with each other, the film peeling yield was reduced to about 60% of the whole.

  Examples of the insulating film formed on the side of the ridge stripe part include oxides (oxides such as silicon, zirconium, tantalum, yttrium, hafnium, aluminum, and gallium) and nitrides (nitrides such as aluminum and silicon). Alternatively, a film made of oxynitride (oxynitride such as aluminum or silicon) can be used.

  In the first to tenth embodiments described above, the stripe width of the ridge stripe portion 111 is exemplified as about 1.2 to 2.4 μm. However, the present invention is a broad area used for lighting applications and the like. The present invention can also be suitably applied to a nitride semiconductor laser element of the type (the stripe width of the ridge stripe portion 111 is about 2 to 100 μm).

  In the first to tenth embodiments, the formation temperature of the coat film 114 is preferably 200 ° C. or higher. In this case, the crystallinity of the aluminum nitride crystal or the aluminum oxynitride crystal constituting the coat film 114 can be improved.

  Further, when forming the coat film 114 after forming the electrode structure and the current confinement structure as in the first to tenth embodiments, the formation temperature of the coat film 114 is set from the viewpoint of preventing the destruction of these structures. It is preferable to set it to 500 ° C. or lower.

  As described above, the coating film 114 formed on the light emitting portion made of the nitride semiconductor crystal of the nitride semiconductor laser element contains oxygen such as aluminum oxynitride as well as aluminum nitride. Even if materials are used, nitriding by crystallizing these materials into nitride semiconductor crystals or aluminum oxynitride crystals whose crystal axes are aligned with the nitride semiconductor crystal of the light emitting portion. The COD level of the semiconductor laser device is improved, and the deterioration of the light emitting part can be effectively suppressed over a long period of time.

In the above first to tenth embodiments, an n-type GaN substrate is used as the semiconductor substrate 101. However, in the present invention, a nitride semiconductor crystal and a crystal of a light emitting portion are added to a light emitting portion made of a nitride semiconductor crystal. One feature is that the reliability of the nitride semiconductor laser device is improved by forming a coat film 114 made of aluminum nitride crystals or aluminum oxynitride crystals with aligned axes. Accordingly, the semiconductor substrate 101 and _{Al S Ga t N (s +} t = 1,0 ≦ s ≦ 1,0 ≦ t ≦ 1) is preferably a substrate made of nitride semiconductor represented by the composition formula, coating film 114 From the standpoint of reducing the lattice mismatch and mitigating defects and strain, it is preferable to use a nitride semiconductor substrate containing aluminum such as an AlN substrate or an AlGaN substrate as the semiconductor substrate 101.

  In the first to tenth embodiments described above, a nitride semiconductor laser element is manufactured by sequentially laminating nitride semiconductor layers on a semiconductor substrate 101 made of a nitride semiconductor. According to the growth surface of the layer, the surface state of the nitride semiconductor layer stacked on the growth surface of the semiconductor substrate 101 also changes, and the crystallinity of the coat film 114 formed on the side surface of the nitride semiconductor layer can also change. . Therefore, it has been found that the growth surface of the semiconductor substrate 101 of the nitride semiconductor laser element can affect the crystallinity of the coat film 114. Here, the growth surface of the nitride semiconductor layer of the semiconductor substrate 101 made of a nitride semiconductor is a C plane {0001}, an A plane {11-20}, an R plane {1-102}, or an M plane {1-100}. Preferably, the off-angle of the growth surface is preferably within 2 ° from any one of these crystal faces.

  In addition, when expressing a crystal plane and a direction, it should be expressed by adding a bar on a required number, but since there are restrictions on expression means, in this specification, the required number is used. Instead of the expression with a bar on top, the symbol “-” is added in front of the required number.

  In the first to third embodiments, the aluminum oxide film 115 is formed on the coat film 114 in order to control the reflectance. For example, an aluminum oxide film or a silicon oxide film is formed. Composition with titanium oxide film, hafnium oxide film, zirconium oxide film, niobium oxide film, oxide film such as tantalum oxide film or yttrium oxide film, nitride film such as aluminum nitride film or silicon nitride film, and coat film 114 At least one selected from the group consisting of an oxynitride film such as an aluminum oxynitride film or a silicon oxynitride film may be formed, and the film may not be formed on the coat film 114. Also good. Further, a magnesium fluoride (MgF) film may be formed on the coat film 114 as a film made of fluoride.

  For example, as an example, an aluminum oxynitride film having a thickness of 20 nm and an oxygen content of 10 atomic% is used as the coat film 114, and a silicon nitride film having a thickness of 150 nm is formed on the coat film 114. As described above, since the silicon nitride film has high moisture resistance and low oxygen permeability, when a silicon nitride film is formed on the coat film 114 made of an aluminum oxynitride film, light due to transmission of oxygen or the like is emitted. It is thought that oxidation of the emission part can be suppressed.

  In the present invention, when the nitride semiconductor light emitting device is a nitride semiconductor diode device, the coat film containing the aluminum nitride crystal or the aluminum oxynitride crystal is used as the light emitting surface of the nitride semiconductor diode device (light Formed on the extraction surface). Here, the light emitting surface refers to a surface from which light is extracted from the nitride semiconductor diode element, and may be any of an upper surface, a lower surface, or a side surface of the nitride semiconductor diode element. In addition, the emission wavelength of the nitride semiconductor diode element (the wavelength of light having the highest emission intensity) is not limited, and can be applied without problems even in the ultraviolet wavelength range or visible wavelength range of about 360 nm. For the same reason as described above, it is preferable that the aluminum nitride crystal or the aluminum oxynitride crystal of the coat film is aligned with the nitride semiconductor crystal constituting the light emitting surface, and the crystal axis is aligned. Is preferably 6 nm or more and 150 nm or less. In the nitride semiconductor diode element of the present invention, for example, a coat film containing an aluminum oxynitride crystal is formed to a thickness of 6 nm, and an aluminum oxide film having a thickness of 80 nm is formed thereon. it can.

  In the present invention, when the coat film is made of aluminum oxynitride crystal, the oxygen content is graded (the oxygen content from the interface between the light emitting portion and the coat film toward the outermost surface of the coat film). The amount may be gradually reduced or increased). Actually, the oxygen content in the coating film varies somewhat. Further, it is preferable that the oxygen content in the coating film varies within a range of 35 atomic% or less.

(Embodiment 11)
FIG. 9 is a schematic cross-sectional view of a preferred example of a MIS type HFET device which is an example of the nitride semiconductor transistor device of the present invention. Here, the MIS type HFET element has a configuration in which a GaN layer 72 and an AlGaN layer 73 are sequentially stacked on a semiconductor substrate 71. On the AlGaN layer 73, a source electrode 74 and a drain electrode 75 are disposed with a predetermined space therebetween, and a gate insulating film 77 is formed between the source electrode 74 and the drain electrode 75. A gate electrode 76 is formed on the gate insulating film 77. Each of the GaN layer 72 and the AlGaN layer 73 is an example of a nitride semiconductor in the present invention.

  Here, in the MIS type HFET device of the present embodiment, the nitride semiconductor crystal constituting the AlGaN layer 73 as the gate insulating film 77 and the aluminum nitride crystal or the aluminum oxynitride crystal whose crystal axes are aligned. It is characterized by using a film made of Thereby, generation | occurrence | production of leak current can be suppressed and reliability can be improved. The thickness of the gate insulating film 77 can be, for example, about 10 nm, and is preferably in the range of 2 nm to 50 nm.

As such a gate insulating film 77, for example, a film made of an aluminum oxynitride represented by a composition formula of Al _d O _e N _f (d + e + f = 1, 0 <e ≦ 0.35) can be used. . In the above composition formula, d represents the composition ratio of aluminum (Al), e represents the composition ratio of oxygen (O), and f represents the composition ratio of nitrogen (N).

  The gate insulating film 77 can be formed by a method similar to that of the coating film 114 in Embodiment 1.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  According to the present invention, a nitride semiconductor light emitting device capable of obtaining sufficient reliability even at high temperature and high output drive, a method for manufacturing a nitride semiconductor light emitting device for manufacturing the nitride semiconductor light emitting device, and A nitride semiconductor transistor device capable of improving reliability can be provided.

  In addition, the present invention provides a window structure (for example, the composition of the active layer in the vicinity of the end face used in a GaAs-based semiconductor laser device, averages the band gap to increase the COD level at the end face portion including the light emitting portion. It is considered that the present invention can also be applied to a nitride semiconductor laser device having the above structure.

71 Semiconductor substrate, 72 GaN layer, 73 AlGaN layer, 74 source electrode, 75 drain electrode, 76 gate electrode, 77 gate insulating film, 78 insulating film, 79 p-side electrode, 100 nitride semiconductor laser element, 101 semiconductor substrate, 102 Buffer layer, 103
n-type cladding layer, 104 n-type guide layer, 105 multiple quantum well active layer, 106 p-type current blocking layer, 107 p-type cladding layer, 108 p-type contact layer, 109 insulating film, 110 p electrode, 111 ridge stripe portion, 112 n electrode, 113, 116 end face, 114 coat film, 115, 118 aluminum oxide film, 117 aluminum oxynitride film, 119 highly reflective film, 200 film formation chamber, 201 gas introduction port, 202 microwave introduction window , 203 Magnetic coil, 204 Al target, 205 heater, 206 sample, 207 sample stage, 208 RF power supply, 209 gas exhaust port, 210 microwave.

Claims (2)

In the nitride semiconductor light emitting device in which the coat film is formed in the light emitting portion,
The coat film is made of aluminum nitride crystal or aluminum oxynitride crystal,
Furthermore, the coating film has a crystal axis aligned with the nitride semiconductor crystal constituting the light emitting portion.   The nitride semiconductor light emitting device according to claim 1, wherein an amorphous film is formed on the coat film.